A common problem in the utilization of modern telephone sets is that of a telephone user (also referred to as a called party) who, while engaged in a first call, receives a second call. The called party's choices are to hang up on the first calling party to answer the second call, to place the first calling party on hold to answer the second call, or to transfer the second call to a secretary or a message answering system such as a voice mail system. The first two alternatives are not normally convenient because they represent inappropriate telephone etiquette. The last alternative is undesirable because it often results in "telephone tag," where two individuals periodically try to contact each other via the telephone and fail because the other person is again on the telephone. Much time is wasted in institutional and corporate settings due to telephone tag. In such environments, telephone conversations often do not last for long periods of time; hence, if the second calling party could wait for a convenient amount of time, the called party could then finish the first call and proceed with the second call.
Modern customer switching systems have provided many helpful aids in attempting to overcome the above problem. Systems such as the AT&T System 85 Communication System with an attached AT&T AUDIX system (voice mail system) are capable of displaying the name of the second calling party on the alpha-numeric display of an electronic telephone set in response to actuation of the "inspect mode" button. The called party decides from the displayed name if she/he will terminate the first call in order to answer the second call, place the first call on hold to answer the second call, or transfer the second call to the voice mail system by actuation of the "send all calls" button. If the second call is transferred to the voice mail system, that system transmits a prerecorded announcement to the second calling party stating that the called party is busy. The system also gives the second calling party the opportunity to leave either a voice mail message or be connected to the called party's secretary. The second calling party indicates his/her choice to the voice mail system by actuating the appropriate multi-frequency dialing buttons on his/her telephone. The voice mail system is useful for brief, but not extended, messages.
U.S. Pat. No. 4,661,975 discloses a system that provides similar capabilities to those previously described but are provided for an analog multi-frequency dialing telephone set. In the disclosed system, the called party who, while engaged in a first call receives a second call, can via a multi-frequency key pad (1) send busy tone to the second calling party and terminate the second call, (2) send a prerecorded message to the second calling party and terminate the second call, (3) transfer the second call to an alternate station, or (4) place the first call on hold to answer the second call by a flash hook operation.
None of the above alternatives are wholly satisfactory from the called party's viewpoint.